1. Field of the Invention
The present invention relates to axially-compressible coil carriers for use in yarn winding machines. More specifically, the invention relates to such coil carriers which are dimensioned to resist elongation when wound with yarn.
2. Related Art
Coil carriers having two end rings with a shell therebetween are well known. In an axially-compressible coil carrier, the shell typically is built of a number of coaxial carrier rings with neighboring rings being fixed to each other by inclined struts. Examples of such coil carriers are disclosed in U.S. Pat. No. 4,702,433; German Offenlegungsschrift 42 19 844; and Europaische Patentschrift 0 233 365; as well as co-pending U.S. patent application Ser. No. 08/078,982, now U.S. Pat. No. 5445,335, which is incorporated herein by reference in its entirety.
Coil carriers can be provided with end rings at each end which thrust together or interlock. In the case of interlocking end rings, the outer diameter of the interlocking collar of one end ring can be matched with the inner diameter of the receiver of the other end ring so as to enable a thread reserve to be accommodated on the collar. For this purpose, a thread reserve groove can also be installed on the collar, as described in U.S. Pat. No. 4,702,433.
Coil carriers of the type described above are wound with yarn, and can then be subjected to a heat or wet treatment, for example a dye bath in which the yarn is dyed by the bath passing through the coil carrier. The yarn is loaded or wound onto the coil carrier by an automatic winding machine. After it has been loaded with yarn, the coil carrier is automatically released by the winding machine. For technical reasons the tolerances of modern winding machines as to the length of the coil carriers are very narrow. In fact, it has been found that winding yarn onto an axially-compressible coil carrier leads to elongation of the coil carrier. Due to this elongation, the loaded coil carrier actually may become clamped in its position in the winding machine, preventing it from being automatically released for further processing. This problem has not been recognized, much less addressed or solved by the prior art. It is to the solution of this problem that the present invention is addressed.